1. Field of Invention
The present invention relates to light emitting diode assemblies, light strings comprising a plurality of light emitting diode assemblies, and related methods.
2. Description of Related Art
Light emitting diodes (LEDs) are increasingly employed as a basic lighting source in a variety of forms, including decorative lighting, for reasons among the following. First, as part of an assembly, LEDs have a very long lifespan, compared with common incandescent and fluorescent sources. For example, a typical LED lifespan is at least 100,000 hours. Second, LEDs have several favorable physical properties, including ruggedness, cool operation, and ability to operate under wide temperature variations. Third, LEDs are currently available in all primary and several secondary colors, as well as in a “white” form employing a blue source and phosphors. Fourth, with newer doping techniques, LEDs are becoming increasingly efficient, and colored LED sources currently available may consume an order of magnitude less power than incandescent bulbs of equivalent light output. Moreover, with expanding applications and resulting larger volume demand, as well as with new manufacturing techniques, LEDs are increasingly cost effective.
Conventional LEDs are typically constructed using steel or coated steal contacts or frames. LED contacts are also available in copper or copper-alloys, although these materials generally are considered undesirable because of their higher cost and incompatibility with some automated LED manufacturing equipment and certain types of LED die material.
LED-containing holiday and decorative light sets, such as used for decorative purposes such as for Christmas lighting, typically use copper-alloy contacts to transfer electricity from the lead wires to the LED lamps. Although manufacturers take efforts to seal the contacts and connections against moisture and airborne contaminants, it is difficult if not impossible to achieve completely and consistently a moisture and contaminant seal.
LED-based light strings also present other drawbacks. For example, U.S. Pat. No. 5,495,147 entitled LED LIGHT STRING SYSTEM to Lanzisera (“Lanzisera”) and U.S. Pat. No. 4,984,999 entitled STRING OF LIGHTS SPECIFICATION to Leake (“Leake”) describe different forms of LED-based light strings. In both Lanzisera and Leake, exemplary light strings are described employing purely parallel wiring of discrete LED lamps using a step-down transformer and rectifier power conversion scheme. These and all other LED light string descriptions found in the prior art convert input electrical power, usually assumed to be the common U.S. household power of 110 VAC to a low voltage, nearly DC input.